Receiver for wireless telegraphy



J. L. HOGAN, JR.

RECEIVER FOR WIRELESS TELEGRAPHY.

APPLICATION FILED FEB. 15. I9I8.

Patented Dec. 28, 1920.

3 SHEETS-SHEET I.

1 O O 0 Q M WW N E V WITNESSES J. L. HOGAN, .IR.

REGEIVER FOR WIRELESS TELEGRAPHY.

APPLICATION FILED FEB. I5, 1918.

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B F F l n w 1 n w w c 3% as :7 5 5 4 3 5 3 3 3 J. L HOGAN, JR.

RECEIVER FOR WIRELESS TELEGRAPHY.

APPLICATION FILED FEB. 15. 1918. 1,363,319.

Patented D60. 28, 1920 3 SHEET$-SHEET 3- FIGIS WITN ESSES INVENTOR UNITED STATES PATENT OFFICE.

H L- H In, or NEW YORK. N. ASSIGNOR To sAmUEL M. KINTNER: AND HALSEY m. BARRETT, EEcEIvEEs or ATIONAL ELECTRIC SIGNALING COMPANY.

RECEIVER FOR WIRELESS TELEGBAI'HY.

Specification of Letters Patent.

Patent-ed Dec. 28, 1920.

Original application filed July 14. 1916, Serial No. 109,259. Divided and this application filed February 15, 1918. Serial No. 217,436.

To all whom it may con cern Be it known that I, JonN L. HOGAN, Jr... a resident of New York, in the county of Kings and State of New York, have invented a new and useful Improvement in Receivers for \Vireless Telegraphy, of which the following is a specification.

This invention relates to receivers for radio telegraphy or telephony operating on the beats or heterodyne principle. The object of the invention is the production of local sustained or undamped high frequency oscillations, at the receiving station, their coordination with the receiving apparatus per 86, and their control, by the use of amplifying relays together with associated resonating circuits.

This application is a division of my application berial No. 109,259, filed July 14, 1916.

It is a well known physical principle that any amplifying relay may be associated with a frequency determining element in such a manner as to produce sustained os- (-illations having their frequency determined by the periodic element of the combination. Thus, a telephone relay of the microphone type may have its input and output circuits coupled so that a portion of the amplified telephone current of the output circuit will be carried back into the input or control circuit, and will thereby operate to keep the apparatus in sustained oscillation. In such an arrangement the period of vibration may be determined by the natural period of the relay transmitter or receiving diaphragm, or in some other way, such as by the time period of the air column existing between diaphragms associated with the magnetic control and microphonic elements, respectively, of the relay.

In this same way, an amplifying relay which is aperiodic may be forced to remain in sustained oscillation of a definite period by associatin with it input and output circuits having tdieir electrical constants adjusted by ca acity and inductance so as to possess a cefinite resonant frequency.

Within limits fixed largely by the inertia of the relaying element, the period of vibration of such a system can be varied merely by changing the natural period of the associated resonant circuits.

All of this is well known in the art, and

may be applied to the operation of such vacuum tube relays as those described by De Forest, Von Lieben, Reisz, Langmuir and others. Vacuum tube relays of this character have practically zero inertia, and are therefore suitable for the production of sustained oscillations of radio frequency 6., from. approximately 20,000 cycles per second upward). Sustained oscillations of this type are useful in radio telegraphy and radio telephony, at receiving stations. for the practice of heterodyne or beats reception in accordance with the principles described in United States Patents Nos. 1,050,411 and 1,050,728, January 11, 1913, to Reginald A. Fessenden and 1,141,717, June 1, 1915, to John IV. Lee and myself.

I have discovered that vacuum tube relays of this character operate most satisfactorily for the production of sustained oscillations when both their input and output elements are associated with circuits which are definitely tuned. In order to secure the best effect, it is necessary to readjust both input and output circuits as to period, if the frequency of oscillation is to be changed. I have found that this may be conveniently effected, among other ways, by use of the single-variable tuning principles set forth 111 my prior Patent 1,014,002, January 9th, 1912, by the use of which principles the frequency of the oscillations produced may be varied over a wide range by a single motion without disturbing the conditions of resonance in the system. I have further discovered that the best operation of vacuum tube or similar relays, according to the singing relay action above described, is secured when the tuned circuits associated with the input and output circuits are closed in themselves, and do not include serially the vacuum discharge path. I have further discovered that this same circuit arrangement tion; Figs. 2 and 3 are similar views of two other arrangements of such receiver; Fig. 4 illustrates the receiving circuits of Fig. 3 with a high frequency alternator substituted for the oscillation generator of Fig. 3; and Fig. 5 illustrates a receiver which combines the local oscillator of Fig. 1 with the circuits of Fi 2.

In Fig. 1 there is shown a vacuum tube relay represented by the incandescent lamp filament 1, the plate 2, and the perforated screen or grid-like intermediate electrode 3, all of which are inclosed within the evacuated vessel 4:. Associated with the filament 1 for the purpose of heating it, is the battery 5, whose current output is controlled by the variable resistance 6. In series between the filament 1 and the plate 2 are the high potential battery 7 and the inductance coil 8. The inductance coil 9 is connected between the filament and the intermediate electrode 3 and is coupled magnetically to the coil 8. Shunted across inductance 8 is the variable condenser 10, and shunted across inductance 9 is the variable condenser 11. These two condensers are arranged to be moved simultaneously by the pivoted levers 12 and 13 and the connecting bar 14.

The closed circuit of the output electrode includes a small inductance 8 which is coupled to the coil 15 in series with the antenna 16, loading coil 17, primary 25, and earth 18. The primary 25 is coupled to a rectifying circuit comprising the secondary 26, tuning condenser 27, detector 28, stopping condenser 29, and telephone 30. The entire arrangement of Fig. 1 forms a receiver operative upon the principles outlined in the prior patent to John WV. Lee and myself No. 1,141,717.

In the operation of this arrangement, when the circuit of the battery 7 is established an electrical impulse is caused to act upon the closed resonant circuit 8, 10, and sets up in the closed circuit 9, 11, a sympathetic oscillation of the same frequency. When the effective resonant period of the circuit associated with the intermediate electrode 3 is substantially the same as that of the circuit associated with the plate electrode 2, transfer of energy is effected most efficiently. The induced oscillations in the circuits 9, 11, apply corresponding poten tials to the intermediate electrode 3; the direction of winding of coil 9 being so chosen with respect to that of coil 8 that the voltage impulses applied to 3, result in a continued sustained oscillation of the closed circuits. The frequency of this oscillation is determined by the effective natural periods of the circuits 8, 10 and 9, 11, (as modified by the elements connected to them), and the strongest and most uniform oscillations are produced when the two circuits have, substantially the same effective frequency of vibration. I-therefore prefer to make the effective inductance of the coil 8 equal to that of coil 9, and the effective-capacity of condenser 10 equal to that of condenser 11. It is necessary in practice to varyslightly from absolute identity of the inductances and of the capacities, because of the effects of coupling reaction and the natural capacity of the various elements associated with these two closed circuits; what is desired is to have the natural frequencies of the input and output circuits practically the same. Inasmuch asthe maximum effect of the intermediate electrode 3 is secured when the highest voltages are applied to it, I have found it advisable in some cases to make coil 9 of double or triple the inductance of coil 8, and correspondingly to make the capacity of condenser 11 one-half or one-third that of condenser 10. This relation results in maintaining the identity of resonant frequencies, within thelimits indicated above.

The net effect of the adjustments and operations described above is to produce strong sustained oscillations in the circuit 8, 10. ith the arrangement of Fig. 1, the best effects are secured when the natural oscillation frequency of the loaded antenna system is the same as that of -the oscillations produced by the generating system. This agreement in resonant periods may be secured by varying the inductance 17 whenever the frequency of oscillation is changed by alteration of the condensers 10, 11, by movement of the lever system 12, 13, 14.

In Fig. 2 reference numerals remain the same as in Fig. 1, but there is shown a slightly different method of simultaneously varying the oscillation periods of the input and output circuits. The variable condenser 10 is controlled by the insulatin lever arm 13 which carries a contacting bri go 22 serving to connect the contact bar 23 with the contact segments 24. The inductance coil 9 is sub-divided, and its constants are so chosen that each sub-division connected by the operation of the combined switch and condenser control lever 13 will result in a close agreement"in resonant frequency of the closed output circuit 8, 10 (with its associated elements) and the input circuit 3, 9. This agreement in period is secured, preferably, by adjusting the natural period of the coil 9 to agree wlth the various periods secured by adjustment of condenser 10 in connection 'with inductance 8. The effect of coil 9 depends on its natural wave length, which is produced by its inductance in combinations with its distributed capacity, so that changing the point of connection varies both the capacity and the inductance. Hence in both circuits 8 and 9 there is a variation of capacity, though in circuit 9 inductance is varied in addition.

The action of the relay oscillator is the same both in Fi l and Fig. 2. With the arrangement of ig. 2, the single variable tuning principle may be extended to include adjustment of the antenna and closed receiving circuits simultaneously with the ad- 'ustment of wave length of the oscillator. l have found it convenient to arrange the apparatus in such a way that the open and closed receiving circuits remain in tune to a certain definite frequency, while at the same time varying them causes the oscillator to produce continuous sustained waves of a frequency slightly different from that to which the receiver itself is tuned. In this way, by a single motion, it becomes possible to pick-up sustained waves or other signals anywhere within a large range of wave length, merely by moving a single handle or lever. Apparatus arranged to operate in this way should preferably have a certain flexibility of adjustment, so that after the preliminary tuning is done, it will be possible to adjust independently each of the several variables so that the absolute maximum of efficiency is obtained.-

One arrangement of receiving apparatus operating in the way just described is illustrated in Fig. 5, in which parts corresponding functionally to those shown in Figs, 1 and 2 are indicated by similar reference numerals. The receiver here shown. combines the local oscillator of Fig. 1 with the circuits of Fig. 2 and has a single adjustment of frequency for all four circuits involved. Condensers 10, 11, 38 and 27 may be chosen to have the same capacity, and are connected through the arms 12, 13, 40 and 42 and insulating links 14, 39 and 41, so that all of said condensers can be varied by equal increments. Under this equal capacity relation (and choosing condensers 36, 37 and 43, equal in capacity to the antenna 16), if the inductances 9, 8, 25 and 26 are equalized, all four circuits will have the same variation in natural period when the condensers are moved. It is not necessary to have the effective capacity and the effective inductance of each of the four circuits the same. If the inductance of one circuit is twice that of another, it is only necessary to make the efi'ective capacity one-half that of the second circuit, in accordance with the principles set down in my single variable tuner patent. The essential is to keep the periods of all four circuits approximately the same. For heterodyne reception it is desirable to make the periods of the circuits containing the coils 8 and 9 slightly different from the period of the circuits containing the coils 25 and 26. This may easily be done by a small change in either the inductance or the capacity. Further, for this type of receiver, it is advantageous to have all four circuits independently variable to a slight extent. This may be easily arranged for by a frictional mechanical linkage between the links 14, 39, 41 and the various condenser arms, so that the angles of these condenser arms with respect to the horizontal link may be changed slightly. Another mode of variation which can be used is by changing the condensers 36, 37 or 43, or the coils 9, 8 or 26, by an amount which gives the desired change in frequency.

It will be understood that in place of the crystal detector 28, of Figs. 1 and 2, any rectifying or detecting organization may be used. For instance, in Fig. 3, I show a sin gle variable oscillator coupled through the coil 8* to an antenna circuit which has associated with it a regenerating and amplifying rectifier receiver of the audion type. The reference numbers on the lefthand por tion of Fig. 3 are identical with those of Fig. 1, the only added element being the battery 31. The purpose of this source of potential is so to polarize the intermediate electrode 3 that it will have a maximum desirable effect upon the electronic stream flowing from the filament l to the plate 2.

In the right-hand or receiver portion of Fig. 3, the secondary 26 is serially connected through the inductance 9 to the variable tuning condenser 11, which has its terminals connected respectively to the intermediate electrode 3 through the condenser 29 and to the filament 1. The coil 9 is magnetically coupled to the coil 8, which is shunted by the condenser 10 and has its terminals connected to the plate electrode 2 and the high potential battery 7. The battery 7 is connected to the filament 1' through the telephones 30 which may be shunted by the condenser 32. The battery 5 and variable resistance 6" serve to control the heating of the filament.

This receiver, which corresponds in some particulars to the receiver described in prior Patent No. 1,113,149, issued to Edwin H. Armstrong, October 6, 1914, may be operated with the coupling between coil 8 and 9 so adjusted that some of the amplified energy of the electrical beats produced by the reaction of the incoming energy with that supplied from the coil 8, is carried back into the input circuit associated with electrode 3, and so produces a multiplied effect. The amplifying action thus secured in the receiver, when combined with the heterodyne effect, results in exceedingly loud responses from comparatively small amounts of received power. The single variable tuning principle may similarly be applied to the circuits shown, by adjusting the effective frequencies of the several oscillation circuits simultaneously.

Fig. 4 illustrates an arrangementof receiving circuits in which the regenerative receiver operating on the beats principle of Fig. 3, is illustrated, but where in lieu of the exciting oscillator of Fig. 3 there is substituted a high frequency alternator 33 connected in series with condenser and primary inductance coil 35, whlch 1S coupled' to the secondary coil 15 in the antenna. The other parts of this circuit are numbered identically with the corresponding parts of Fig. 3, and operate in the same way. The high frequency alternator 33 here serves as the exciting oscillator, producing with the received oscillations the beats eifect in the receiving circuits.

It is obvious that the oscillation generator of Fig. 1 can be combined with the receiving circuits shown on the righthand side of either Figs. 2 or 3. It is also obvious that any form of amplifying receiver may be used in place of that shown in the righthand portions of Figs. 3 and-4.

By the term resonating in the claims is meant that the circuit is capable of being tuned or adjusted to the frequency of the current existing in it but without necessarily being'adjusted to exactly that frequency, although at least partial resonance is taken advantage of.

What I claim is:

1. In receiving. apparatus for radio communication,-the combination of a receiving antenna, a source of locally generated electrical oscillations comprising an amplifying relay having resonating electrical cir-' cuits associated with its input and output terminals, and a single means for simultaneously varying the electrical periods of said resonating circuits, and a detector and indicator associated with said antenna.

2. In a receiving apparatus for radio communication, the combination of a receiving antenna, a source of locally generated oscillations comprising an amplifying relay with resonating electrical circuits associated with its input and output terminals, the output circuit of said source being associated with the antenna, a single means for simul taneously varying the electrical periods of said resonating circuits, and an electrical rectifier and indicator associated with said antenna.

3. in a receiving apparatus for radio comriods of said resonating circuits, and a detector and indicator associated 'wlth said antenna.

4;. In receiving apparatus for radio communication, the combination of a receiving antenna, a source of locally generated electrical oscillations comprising an amplifying relay having resonating electrical circuits associated with its input and output terminals, a single means for simultaneously varying the electrical periods of said resonating circuits and said antenna, and a detector and indicator associated with said antenna.

In a receiving apparatus for radio communication, the combination of a receiving antenna, of means for locally generating electrical oscillations of slightly different period than the received oscillations comprising an amplifying relay having resonating electrical circuits associated with its input and output terminals, asingle means for simultaneously varying the electrical periods of said resonating circuits and said antenna, and a detector and indicator associated with said antenna.

6. In a heterodyne receiver for wireless signaling, the combination of a receiving antenna, a source of electrical oscillations locally produced, and an amplifying detector system including an amplifying relay .having resonating electrical circuits associated with its input and output electrodes, a single means for simultaneously. varying the electrical periods of said resonating circuits.

R. B. CLAPPERTON, Gno. E. Conn. 

